I'm not sure about the Acer Ring, but to capture your screen all you have to do is press both the "Power" and "Volume Down" buttons at the same time and hold it for about a second. It should then show that it took a screenshot.

"The new update of Android 4.0 also includes several new features that are unique to Acer tablets. The updated tablets will now feature the highly-customizable Acer Ring, making it incredibly natural and easy to get instant access to favorite apps and features. The Acer Ring can be launched with a single touch and lets customers have quick and easy access to apps, surf the web, capture screen images, post photos and status updates to their social networks, and more."

i just had a chat with acer on their site and bugged the heck out of them and asked them about the acer ring for a500. he told me as of now there is no update, then i asked will we see the acer ring on a500... her response was " yes you will be getting the update to include ring"

I attached a screenshot of the response I got from them, I actually had to write them 3 times because apparently I wasn't clear enough in my first couple of emails for them to even understand what I was asking.......seems to me like even the people at Acer support aren't really sure what's going to happen with the ring launcher and who exactly will be receiving it I hope it is something that Acer is going to update on the A500 though, would love to have it , oh well guess we wait and see .

i tried to get a screen shot of the acer ring chat i had with acer support, but i was not able too and ended shutting of the tablet by mistake... anyhow... i was very clear in that i was asking about the acer ring launcher and if it was going to be added to the a500 iconia tab... again, they replied " yes, you willl be getting that update. " who knows... i love tab with or without the ring... hopefully it will be a positive that we do get it... best wishes to all....

Although one could argue that the features in PR only refers to the a200. I'm not saying it says that, I'm just saying one could argue that in terms of "The update is being pushed to Acer Iconia Tab A200 customers over-the-air now" as opposed to " The Acer Iconia Tab A100 7-inch tablet and Acer Iconia Tab A500 10-inch tablet will both be updated in April." which is a separate update. So everything in the PR, one could argue, only refers to the a200.

Although one could argue that the features in PR only refers to the a200. I'm not saying it says that, I'm just saying one could argue that in terms of "The update is being pushed to Acer Iconia Tab A200 customers over-the-air now" as opposed to " The Acer Iconia Tab A100 7-inch tablet and Acer Iconia Tab A500 10-inch tablet will both be updated in April." which is a separate update. So everything in the PR, one could argue, only refers to the a200.

*shrug*

From the article:

Acer says with the ICS update, the A500 and A100 will receive the Acer Ring launcher (seen above) that's already on the A200. The Ring is a customizable launcher that gives quick access to apps, bookmarks and volume controls. There's also an updated weather widget, and you'll have quick-launch app access from the lockscreen (again, like on the A200). There are improvements to photos and videos as well, including the ability to take still images while recording video.